Flora of Australia. 177 



Ulex europaeus, L. (Leguminosae). " Furze or Gorse." 



An important factor in determining the persistence of perennial 

 weeds during dry summers is the depth to which the roots penetrate. 

 Nevertheless, in the case of gorse, the plant seems to withstand dry 

 seasons, even when the roots penetrate only to a small depth. Thus 

 in one case a green clump four to five years old, 2 ft. 6 in. in 

 height and 4 ft. across, was growing on thin soil, with a hard pan 

 subsoil which the roots were unable to penetrate. Their depth 

 varied from 4i to 6 in., without the plant appearing to suffer from 

 the dry summer. On looser soils the roots penetrate much more 

 deeply. The deepest roots were found on a loose soil, with a porous 

 clay sub-soil, in which they attained a depth of 2 ft. 7 in. Under 

 still more favourable circumstances possibly greater depths may be 

 obtained. 



Xanthorrhora australis, R.Br. (Liliaceae). "Grass Tree." 



In addition to the resin produced by this plant other products 

 may be obtained from it, some of which may have an economic 

 value. By distilling the resinous leaf bases with water, Mr. Watt, 

 of Cobden, obtained a dark coloured, strongly smelling grass tree 

 oil, which if it could be obtained cheaply and in abundance might 

 be of some value as an insecticide. The oil itself killed every leaf 

 to which it was applied, viz., grasses, St. John's Wort, sunflower, 

 dahlia and onion weed. Unfortunately the oil does not mix with 

 water, and although water shaken up with it acquires a strong- 

 smell of the oil, it had no effect when sprayed on plants of St. 

 John's Wort, and also did not affect the grass leaves around them. 



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